For example, in a machining apparatus, cutting is performed, while supplying a cutting fluid from a feed tank, and the cutting fluid contains cutting dust in a fine powdery form. The cutting fluid containing fine powdery cutting dust is supplied to the filter device, and the filter device removes the cutting dust and returns the cutting fluid to the feed tank (for example, see Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-Open No. 2001-137743 (pp. 1 to 5, FIGS. 1 to 3)
As such a filter device, for example, there are filter devices that remove cutting dust by a filter film or remove cutting dust by settlement. However, both devices have a problem in that the fine powdery cutting dust contained in the cutting fluid in a large amount cannot be reliably removed in a short time by a small-sized device.
Moreover, the filter film may clog, and when the filter film clogs, the filter device must be disassembled to clean the filter film. Therefore, the filter device needs washing and exchanging work, when the filter device becomes unserviceable.
Furthermore, when the filter film is used repetitively, the filtering accuracy deteriorates, and becomes likely to clog. Therefore, almost all filter films are disposable filter films, and hence there is a problem of cost increase.
In view of the above situation, it is a first object of the present invention to provide a filter device that can separate and reliably remove a large amount of particles in a short time by a small-sized device. It is a second object of the present invention to provide a filter device, which does not need washing and exchanging work, and keeps costs low.